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1. chinaXiv:201711.00007 [pdf]

Topcolor-A ssisted Supersym m etry

Chun Liu
分类: 物理学 >> 基本粒子与场物理学

Ithasbeen known thatthe supersym m etric avor changing neutralcurrent problem can beavoided ifthesquarkstakethefollowing m asspattern,nam ely the #12;rsttwo generations with the sam e chirality are degenerate with m asses around the weak scale,while the third generation is very heavy. W e realize thisscenario through the supersym m etricextension ofa topcolorm odelwith gauge m ediated supersym m etry breaking.

提交时间: 2017-09-17 点击量27下载量20 评论 0

2. chinaXiv:201709.00031 [pdf]

Λb → Σ (∗) c πlν¯ in the heavy quark, chiral, and large Nc limits

Jong-Phil Lee; Chun Liu; H. S. Song
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

The decay of Λb → Σ(∗)c πlν¯ processes are calculated in the framework of heavy baryon chiral perturbation theory with help of the 1/Nc expansion. The decay rate distributions over v · v′ where v and v′ are the 4-vector velocities of Λb and Σ(∗)c respectively, and over the pion and lepton energies are given. The decay branching ratios amount to about 1.21(0.971)% for Λb → Σcπlν¯and 0.798(0.640)% for Λb → Σ∗cπlν¯ by using the baryonic Isgur-Wise function predicted by QCD sum rule (large Nc QCD).

提交时间: 2017-09-17 点击量29下载量18 评论 0

3. chinaXiv:201709.00032 [pdf]

Reanalysis of the Four-Quark Operators Relevant to #3;b Lifetime from QCD Sum Rule

Chao-Shang Huang; Chun Liu; Shi-Lin Zhu
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Λb matrix element of four-quark operator relevant to its lifetime is reanalyzed by QCD sum rule. The new ingredients introduced are that (1) more vacuum condensates are considered; (2) different quark-hadron duality is adopted; and (3) the possible deviation from the vacuum saturation assumption for the four quark condensates is considered. With κ1 = 4 the related hadronic parameter r is calculated to be (3.6 ± 0.9), and the lifetime ratio τ (Λb)/τ (B0) = (0.83 ± 0.04), which is consistent with the experimental data.

提交时间: 2017-09-17 点击量35下载量22 评论 0

4. chinaXiv:201709.00033 [pdf]

Electroweak Symmetry Breaking due to Confinement

Chun Liu
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Within the framework of gauge mediated supersymmetry breaking, we con-sider an electroweak symmetry breaking pattern in which there is no con-ventional μ term. The pattern is made appealing through realizing it as low energy effective description of a supersymmetric Yang-Mills theory which is of confinement. Phenomenological implications are discussed.

提交时间: 2017-09-17 点击量24下载量20 评论 0

5. chinaXiv:201709.00034 [pdf]

Four Light Neutrinos in Singular Seesaw Mechanism with Abelian Flavor Symmetry

Chun Liu; Jeonghyeon Song
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

The four light neutrino scenario, which explains the atmosphere, solar and LSND neutrino experiments, is studied in the framework of the seesaw mech-anism. By taking both the Dirac and Majorana mass matrix of neutrinos to be singular, the four neutrino mass spectrum consisting of two almost degen-erate pairs separated by a mass gap ∼ 1 eV is naturally generated. Moreover the right-handed neutrino Majorana mass can be at ∼ 1014 GeV scale unlike in the usual singular seesaw mechanism. Abelian flavor symmetry is used to produce the required neutrino mass pattern. A specific example of the flavor charge assignment is provided to show that maximal mixings between the #23;μ − #23;#28; and #23;e − #23;s are respectively attributed to the atmosphere and solar neutrino anomalies while small mixing between two pairs to the LSND results. The implication in the other fermion masses is also discussed.PACS numbers: 11.30Hv, 14.60Pq, 14.60.St.

提交时间: 2017-09-17 点击量20下载量17 评论 0

6. chinaXiv:201709.00035 [pdf]

MeV Tau Neutrino in Gauge Mediated Supersymmetry Breaking Model

Chun Liu; H.S. Song
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

A supersymmetric model which naturally accommodates MeV tau neutrino within the framework of gauge mediated supersymmetry breaking is described. The lepton number violation is originally introduced in the messenger sector of the theory. A large slepton-Higgs mixing mass and asmall lepton-higgsino mixing mass are generated at one-loop. Scalar tau neutrino has non-vanishing vacuum expectation value. These results in a non-zero #23;#28; mass which is in the range of (1 − 10) MeV.

提交时间: 2017-09-17 点击量19下载量15 评论 0

7. chinaXiv:201709.00036 [pdf]

Excited heavy baryon spectrum in large Nc heavy quark effective theory

Jong-Phil Leea; Chun Liub; H. S. Song
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

L = 1 excited heavy baryon masses are analyzed by heavy quark and large Nc expansions. In heavy quark limit, mass is parameterized by � and it is expanded further by spin-flavor breaking operators to the zeroth order of 1/Nc. Expanding coefficients will be fixed by more data on the excited baryons in the near future.

提交时间: 2017-09-17 点击量23下载量17 评论 0

8. chinaXiv:201709.00037 [pdf]

Analysis of #3;b → #3;c weak decays in Heavy Quark Effective Theory

Jong-Phil Lee; Chun Liu ; H. S. Song
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

The #3;b → #3;c semileptonic decay is analyzed in the framework of heavy quark effective theory to the order of 1/mc and 1/mb. The QCD sum rule and large Nc predictions to the decay form factors are applied. It argues that the subleading baryonic Isgur-Wise function in the large Nc limit vanishes.The decay rates, distributions and asymmetry parameters are calculated nu-merically. Some of the nonleptonic decay modes are discussed in the end.

提交时间: 2017-09-17 点击量24下载量17 评论 0

9. chinaXiv:201709.00038 [pdf]

EXCITED HEAVY MESONS FROM QCD SUM RULES

Chun Liu
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等

Orbitally excited L = 1 charm mesons are studied by QCD sum rules in the framework of heavy quark effective theory. The meson masses and the strong decay widths are obtained. This talk is based on our works of refs. 1 and 2 collaborated with Y.B. Dai, C.S. Huang, M.Q. Huang and H.Y. Jin.

提交时间: 2017-09-17 点击量18下载量13 评论 0

10. chinaXiv:201711.00008 [pdf]

1/Nc Expansion of the Heavy Baryon Isgur-Wise Functions

Chun Liu
分类: 物理学 >> 基本粒子与场物理学

The 1/Nc expansion of the heavy baryon Isgur-Wise functions is discussed.Because of the contracted SU(2Nf ) light quark spin-flavor symmetry, the universality relations among the Isgur-Wise functions of b ! #3;c and #6;(∗) b ! #6;(∗)c are valid up to the order of 1/N2 c .

提交时间: 2017-09-17 点击量14下载量9 评论 0

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